Researchers at the University of Connecticut have developed a biodegradable pressure sensor that can be implanted in the body and help clinicians to monitor a variety of conditions over extended periods of time. What makes this sensor different from existing ones is that it doesn’t need to be removed and will eventually dissolve in the body, eliminating the risk of infection and the longer recovery associated with an invasive surgical procedure to remove a sensor.
Clinicians can use implantable pressure sensors to monitor a variety of health conditions, including brain swelling as in hydrocephalus, chronic lung diseases, CHF and other heart diseases, and glaucoma. At present, such implantable sensors must be removed later, as they are not biodegradable and sometimes contain toxic components or heavy metals.
“Medical sensors are often implanted directly into soft tissues and organs,” said Thanh Duc Nguyen, a researcher involved in the study. “Taking them out can cause additional damage. We knew that if we could develop a sensor that didn’t require surgery to take it out, that would be really significant.”
The research team built their sensor using molybdenum electrodes and Poly(L-lactide) (PLLA), which is biodegradable, but doesn’t typically have the correct electrical properties for a pressure sensor. Through a process of heating and stretching, the team was able to change the PLLA molecularly, so that it produced an electrical charge when it was squeezed. This characteristic is known as piezoelectricity, a key property for pressure sensors which need to transmit signals when deformed by tissue movement.
The team’s piezoelectric sensor is highly sensitive, and when implanted in a mouse to sense diaphragm movements, it was successfully able to measure respiratory rates, before breaking down into its individual components within four days. The researchers also tested the sensor for safety, and found that it produced only mild inflammation when implanted in mice, and this disappeared four weeks later. At present, the team is working on extending the life of the sensor in the body.
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